0. Add tests for orthogonality in the Peirce decomposition.

1. Add CartesianProductEJA.

2. Check the axioms in the constructor when check != False?

3. Add references and start citing them.

4. Implement the octonion simple EJA.

5. Factor out the unit-norm basis (and operator symmetry) tests once
   all of the algebras pass.

6. The EJA random element method only returns two summands by default.